Fuel cells are devices that convert the fuel and oxidant to electrical energy. Most efficient fuel cells use pure hydrogen as the fuel and oxygen as the oxidant. Unfortunately use of pure hydrogen has a number of known disadvantages not the least of which is its relatively high cost. Consequently, attempts have been made to operate fuel cells using other than the pure hydrogen as the fuel. For example, attempts have been made to use hydrogen rich gas mixtures obtained from steam reforming methanol as a fuel cell feed. These attempts, however, have not resulted in a practical system because carbon monoxide which is present in such gas mixtures degrades cell performance, even in relatively low concentrations.
It is an object of the present invention therefore to treat a CO-containing, hydrogen rich gas mixture to lower the CO content of the mixture to render it more suitable for use in fuel cell systems.
It is another object of the present invention to provide a method for lowering the CO content of a hydrogen rich gas stream in a single step.
It is another object of the present invention to provide a method for reducing the CO content of a hydrogen rich gas stream which is energy efficient.
Still another object of the present invention is to provide a fuel cell system in which a CO-containing, hydrogen-rich gas stream is subjected to a step in which the CO in the gas stream is oxidized to CO.sub.2. In this way, the concentration of CO in the gas stream is lowered to below about 5 ppm in order to provide a substantially CO-free, hydrogen rich gas stream to a fuel cell.